lib/src/vector_math/vector.dart

/*
  Copyright (C) 2013 John McCutchan <john@johnmccutchan.com>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/

part of vector_math;

/// 2D dot product.
double dot2(Vector2 x, Vector2 y) => x.dot(y);

/// 3D dot product.
double dot3(Vector3 x, Vector3 y) => x.dot(y);

/// 3D Cross product.
void cross3(Vector3 x, Vector3 y, Vector3 out) {
  x.crossInto(y, out);
}

/// 2D cross product. vec2 x vec2.
double cross2(Vector2 x, Vector2 y) {
  return x.cross(y);
}

/// 2D cross product. double x vec2.
void cross2A(double x, Vector2 y, Vector2 out) {
  var tempy = x * y.x;
  out.x = -x * y.y;
  out.y = tempy;
}

/// 2D cross product. vec2 x double.
void cross2B(Vector2 x, double y, Vector2 out) {
  var tempy = -y * x.x;
  out.x = y * x.y;
  out.y = tempy;
}

/// Sets [u] and [v] to be two vectors orthogonal to each other and
/// [planeNormal].
void buildPlaneVectors(final Vector3 planeNormal, Vector3 u, Vector3 v) {
  if (planeNormal.z.abs() > Math.SQRT1_2) {
    // choose u in y-z plane
    double a = planeNormal.y*planeNormal.y + planeNormal.z*planeNormal.z;
    double k = 1.0/Math.sqrt(a);
    u.x = 0.0;
    u.y = -planeNormal.z*k;
    u.z = planeNormal.y*k;
    v.x = a*k;
    v.y = -planeNormal[0]*(planeNormal[1]*k);
    v.z = planeNormal[0]*(-planeNormal[2]*k);
  } else {
    // choose u in x-y plane
    double a = planeNormal.x*planeNormal.x + planeNormal.y*planeNormal.y;
    double k = 1.0/Math.sqrt(a);
    u.x = -planeNormal[1]*k;
    u.y = planeNormal[0]*k;
    u.z = 0.0;
    v.x = -planeNormal[2]*(planeNormal[0]*k);
    v.y = planeNormal[2]*(-planeNormal[1]*k);
    v.z = a*k;
  }
}